Answer: x = -19
Step-by-step explanation: When you're asked to solve for x in an equation, what you're really being asked to do is get x by itself on one side of the equation.
In this problem since 4 is being added to x, in order to get x by itself, we must subtract 4 from the left side of the equation and when we subtract 4 from the left side of the equation, remember that we must also subtract 4 from the right side of the equation.
So on the left, +4 and -4 cancels out and on
the right, -15 - 4 simplifies to -19.
So x = -19.